Experience sharing about index operations in Mysql

Indexes do not depend on storage space. If used properly, they can improve query efficiency.

This article will show the addition and deletion operations of indexes

1. Query on mysql Index information

Command:

 show index from staff;
Output:
mysql> show index from staff;
Empty set (0.00 sec)

2. Add a common index

Command:

create index idx_staff on staff(id);

3. Add UNIQUE index

Command:

create unique index idx_unique_staff on staff(id);

Tips:

You cannot use the CREATE INDEX statement to create a PRIMARY KEY index

4. Add the index through the alter command

Command:

alter table staff add index idx_staff_byAlter (id);

5. Delete index

Command 1:

 drop index idx_staff on staff;

6. Command 2 :

alter table staff drop index idx_staff_byAlter;

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